In conventional mechanical seal configurations, various types of rotating equipment, such as pumps and compressors, are provided with mechanical seals to prevent or impede leakage of process fluid that might otherwise migrate along the shaft of the rotating equipment. In many of these mechanical seals, a dry gas serves as a barrier fluid or buffer fluid next to a pair of relatively rotatable mechanical seal rings, which fluid serves to greatly minimize, if not eliminate leakage along the shaft. Such mechanical seals include a barrier fluid chamber for receiving the dry gas therein from a gas supply system. This gas supply system supplies the gas to the mechanical seal at a particular pressure and flow rate which maintains an adequate supply within the fluid chamber of the seal.
During normal conditions, leakage of process fluid past the seal faces into the barrier fluid chamber is prevented by the higher pressure of the barrier fluid both statically when the shaft is not rotating and dynamically during shaft rotation. Under such normal conditions, small amounts of barrier fluid may flow across the seal faces into the process fluid, although this barrier fluid is of a type of fluid which is not a contaminant if present in the process fluid. However, if inadequate barrier fluid pressure is present, a reverse flow of process fluid may occur where the process fluid undesirably leaks into the barrier fluid chamber. For example, in a compressor, there may be a period when the compressor is being started or is being shutdown, and during these periods, there may not be adequate barrier fluid pressure and flow to prevent a reverse flow of process fluid leaking into the barrier fluid chamber.
It is an object of the invention to maintain an adequate flow rate of the barrier fluid, even at low-feed operating conditions of the rotating equipment or at start up of such equipment.
The invention relates to an improved gas supply system which, in particular, relates to an improvement in a gas supply system sold by the assignee of the present application under the trademark AMPLIFLOW™. In the known AMPLIFLOW system, the seal supply system turns on the gas supply at a pressurized flow rate at the time of, for example, compressor case pressurization wherein the seal supply system remains on during compressor rotation. At the point in time when pressure is adequate, the AMPLIFLOW system can be turned off while the compressor system continues running. During unit shutdown of the compressor system, the AMPLIFLOW system may be turned on again as compressor rotation comes to a stop and after rotation is completed, then the AMPLIFLOW system can be turned off again.
More particularly as to the present invention, the invention relates to an improved supply system having an intensifier comprising a pair of mechanically inter-connected pneumatic pressure cylinders which comprise a drive cylinder that affects movement of a boost cylinder wherein the displacement of these mechanically interconnected pistons in the drive cylinder and boost cylinder intensifies the pressure being discharged by the boost cylinder and supplied as a barrier fluid to the mechanical seal.
While a pneumatic four-way valve has been used in the known AMPLIFLOW system to control the operation of the drive cylinder, this pneumatic four-way valve, as shown in FIGS. 3-5 of the present application suffers from disadvantages associated therewith as discussed in more detail herein.
The invention relates to an improved intensifier using an improved control valve and operating system therefore which provides advantages over the prior art. In this regard, the invention relates to an intensifier using a fast-acting 5/2-way solenoid valve having a feed back loop connected to a control system which includes a micro processor that controls valve actuation. As discussed herein, this system provides for remote operation and monitoring and improves the overall performance of the fluid control system.
Other objects and purposes of the invention, and variations thereof, will be apparent upon reading the following specification and inspecting the accompanying drawings.
Certain terminology will be used in the following description for convenience and reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the arrangement and designated parts thereof. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.